Have you tried going into your admin console (
http://www.yourdomain.com/login.html) and deleting your billing info and canceling your account in there?
RealityCheckNetwork is a fucking dope service .... BECAUSE they make things so automated. I have never had a problem getting customer support from them, and the fact that they aren't replying to you is fuckin lame. But at least use the resources you have at hand
-Phil